Chemical composition



Patented Aug. 8, 1950 STATES OFF-HIE by'mesneassignments, tattle-UnitedStates of" America as represented by-theScretary-of War No Drawing.Application December-11,1945, Serial No. 634,409.

ZCIaims. 1

This inventionrelates tobleaching compositions and more particularly toa bleach solution which will adhere to surfaces to increase the time ofcontact of 'thesurface" with the bleach.

An object of this" invention is to produce an adherent bleachcompositioniwhich is economical and. whichwill adhere to vertical andslanting surfaces.

Afurther object of this invention is todevelop a bleach slurry whichwill effectively decontami nate surfaces which have been exposed to theaction of vesicant agents.

My composition has been developed to treat surfaces which have beenexposed to the action of vesicant agents such as mustard gas(C1CH2CH2SCH2CH2C1) to decontaminate said surfaces in order thatpersonnel may exist in the contaminated area without wearing protectivecloning. The composition, however, can also be used for bleachingvertical surfaces since the bleachzwater slurry is very adherent andwill expose the surfaces to the action of the bleach for a comparativelylong period of time. My bleach slurry does not run off of said surfaces,its action is therefore, intensified and more efiective results areobtained.

It has been known in the past to thicken bleach solutions by theaddition of such compounds as fullers earth, Iceland and Irish moss,kieselguhr,

diatomaceous earth, glutinative substances and colloidal compositionsobtained from bentonite. However, the addition of these substances,usually in very large proportion, to bleach solutions has been performedwith the object of making the bleach solution nearly dry, absorbent tooily matter, and to dilute the action of the bleach to obtain lessdestruction of the material to be treated.

The object of my invention is entirely different. Asbestos is added tothe bleach solution in very small proportion in order to render thebleach water slurry more adherent and to extend the time of action ofthe bleach compositon on vertical and slanted surfaces. Furthermore, inthe preferred embodiment of my invention, the ad herent bleachzwaterslurry is tobe used to decontaminate surfaces exposed to vesicantagents.

I have discovered that the addition to conventional bleach slurries of asmall amount of asbestos fiber produces an adherent suspension whichincreases the effectiveness of the slurry when applied to slanting andvertical surfaces. In order to increase the action of my composition, aminor amount of a wetting agent can be added. Any wetting agent whichdoes not react with, the bleaching powder may be employed.

Since concentratedbleachslurries have" a tendency to gel, ananti-settingzor-antigelling agent may be added.

I have foundthat' the adherence per unit area of bleachzwater slurriesto verticalsurfacesand hence, their. bleachng, anddecontaminatngrefiiciency, .is'greatly increased. by the addition of. asmall amount of finely divided asbestos fiber. For example, theadherenceper unit area to a vertcal surface of Ta 40:60 blacli:waterslurry. is approximately doubled by the incorporation of 0.25% ofMikro-pulverized asbestos fiber and is almost quadrupled by theincorporation of 0.75% of the same fiber. An asbestos thickened 40:60bleachzwater slurry has an adherence to vertical surfaces which is equalto or greater than that exhibited by a :50 bleachzwater slurry. The50:50 bleachzwater slurry however, is not only more wasteful in the useof bleach, but also is much more difficult to handle.

The preferred embodiment of my invention is illustrated by the followingexample.

ExampZe.-A bleachzwater slurry is prepared by adding 1250 parts ofbleaching powder (chloride of lime containing 35% available chlorine) toa solution of 6.3 parts of sugar in 1870 parts of water, the sugarserving to prevent setting, or gelling, of the slurry. After agitatingthe mixture vigorously for 15 to 20 minutes, 3.1 parts of finely dividedasbestos powder (Canadian Government specification 5-K, grade 0-0-12-4,which has been Milne-pulverized and has a maximum fiber length of 400microns with 93% having a fiber length less than microns), and 0.31 partof sodium dodecyl sulfate are added and mixing continued until a uniformslurry is obtained, this usually requirng only 5 to 10 minutes. Themixture is then strained through a screen having openings in diameterand sprayed onto a vertical glass plate. After allowing the excess pasteto drain from its surface, the plate is weighed. On the basis of theweight of the moist film and the proportion of dry bleach in theoriginal slurry, the amount of dry bleaching powder adhering to a unitarea of the vertical plate is calculated to be 6.6 oz./sq. yd. A film ofbleach applied in the same manner from a control composition containingno asbestos thickener amounts to only 2.7 oz./ sq. yd.

y ype of asbestos fiber which has a particle size approaching that givenin the example can be used in my invention. Asbestos fiber according toCanadian specifications 5-K, grade 0-0- 12-4, contain fibers of a sizesuitable for use in bleach water siurries to be sprayed from small scaleapparatus, but the fibers are too large for use in slurries to besprayed from large scale apparatus. For use in large sprayers such asthose of 400-gallon capacity, the asbestos fiber should be reduced to amaximum length of 400 microns to prevent clogging the filters in thespray apparatus, Satisfactory particle size can be obtained bysubjecting'ccmmercial fiber to disintegration in a Mikro-pulverizer (amachine which is obtainable in the commercial market).

The proportion of asbestos fiber to be incorporated in the bleach: Waterslurry is not fixed but should be small (roughly on the order of A; to5%). This proportion depends-on several factors such as, for example,the concentration of the slurry, the degree of thickening desired andthe particle size of the asbestos. By way of illustration, 0.25% of theMilne-pulverized asbestos of the example is about as effective as 0.75%of grade 0-0-12-4 asbestos.

Instead of sodium dodecyl sulfate, any Wetting agent can be employed inminor amounts if it is not reactive with the bleaching powder used.

Sugar can be replaced by any of the known anti-setting or anti-gellingagents.

The nature Of this invention has been broadly outlined above, thepreferred embodiments have been described and it will be apparent thatcertain modifications and additional formulations will suggestthemselves to those skilled in the art. Accordingly, it i intended thatthe foregoing description shall be interpreted as illustrative only andnot in a limiting sense.

I claim:

1. A decontaminant for vesicant gases consisting of approximately 1250parts of bleaching powder having available chlorine, 6.3 parts of sugar,3.1 parts of comminuted asbestos powder having a maximum fiber length of400 microns, .31 part of sodium dodecyl sulfate and 1870 parts of water.I V 2. A decontaminant for vesicant gases consisting of, from 3.1 to 155parts of asbestos, 1250 parts of bleaching powder'having approximatelyof available chlorine, 6.3 parts of sugar, .31 part of sodium dodecylsulfate, and 1870 of water.

. ROBERT N. MACDONALD.

REFERENCES CITED The following references are of record in th file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,320,280 Kalusdian May 25, 19432,351,924 Carnauh June 20, 1944 OTHER REFERENCES

1. A DECONTAMINANT FOR VESICANT GASES CONSISTING OF APPROXIMATELY 1250PARTS OF BLEACHING POWDER HAVING 35% AVAILABLE CHLORIDE, 6.3 PARTS OFSUGAR, 3.1 PARTS OF COMMINUTED ASBESTOS POWDER HAVING A MAXIMUM FIBERLENGTH OF 400 MICRONS, .31 PART OF SODIUM DODECYL SUFATE AND 1870 PARTSOF WATER.